At high frequency communication rates, conductive paths such as coaxial wire, twisted pair wire, and circuit board traces, take on a characteristic impedance which must be matched with either source or destination termination resistors to ensure minimal signal reflection. In high speed supercomputers, such as the type manufactured by Cray Research, Inc., the Assignee of the present invention, nearly all conductive paths require such source or destination termination. A significant problem with source or destination termination is that a large portion of the circuit board surface is taken up by resistor components.
In high speed supercomputers, nearly all available space on circuit boards must be given over to logic elements. To maximize speed, the length of conductive paths between logic elements must be short to minimize signal propagation delay. Therefore, integrated circuits must be mounted close together on circuit boards. In the prior art, terminating resistor components are wasteful of circuit board space. Thus, there is a need for integrated circuit packages which contain, as an integral component, terminating resistors of either the source or destination type. The inclusion of terminating resistors must not increase the overall size of the integrated circuit package. Minimizing the "footprint" of each integrated circuit on a circuit board remains a primary goal.